Ferroelectric ceramics and manufacturing method thereof

ABSTRACT

To obtain a piezoelectric film having excellent piezoelectric properties. One aspect of the present invention relates to ferroelectric ceramics including a ZrO 2  film oriented in (200), a Pt film that is formed on the ZrO 2  film and is oriented in (200) and a piezoelectric film formed on the Pt film.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to ferroelectric ceramics and amanufacturing method thereof.

Description of a Related Art

A conventional manufacturing method of a Pb(Zr,Ti)O₃ (hereinafter,referred to as “PZT”) perovskite-type ferroelectric ceramic will beexplained.

A SiO₂ film having a thickness of 300 nm is, formed on a 4-inch Siwafer, and a TiO_(x) film having a thickness of 5 nm is formed on theSiO₂ film. Next, a Pt film having a thickness of 150 nm, oriented in,for example, (111) is formed on the TiO_(x) film, and a PZT sol-gelsolution is applied onto the Pt film by using a spin coater. Spinconditions at this time are such that the wafer is rotated at arotational speed of 1500 rpm for 30 seconds and is rotated at arotational speed of 4000 rpm for 10 seconds.

Next, the applied PZT sol-gel solution is heated and held on a hot plateat 250° C. for 30 seconds to thereby be dried, and moisture is removed,and after that, is additionally heated and held for 60 seconds on a hotplate maintained at a high temperature of 500° C. to thereby performtemporary calcination. A PZT amorphous film having a thickness of 150 nmis produced by repeating this for several times.

Subsequently, an annealing treatment is performed on the PZT amorphousfilm at 700° C. by using a pressurizing-type lamp annealing device (RTA:rapidly thermal anneal) to thereby carry out PZT crystallization. ThePZT film thus crystallized is formed of a perovskite structure (referto, for example, Patent Literature 1).

[Patent Literature 1] WO 2006/087777

[Patent Literature 2] Japanese Patent Laid-Open No. 11-312801

SUMMARY OF THE INVENTION

An aspect of the present invention is to solve the problem of obtaininga piezoelectric film having excellent piezoelectric properties.

Hereinafter, various aspects of the present invention will be explained.

[1] Ferroelectric ceramics including:

a ZrO₂ film oriented in (200);

a Pt film that is formed on the ZrO₂ film and is oriented in (200); and

a piezoelectric film formed on the Pt film.

[2] The ferroelectric ceramics according to [1], wherein a PtO₂ filmoriented in (200) is formed between the ZrO₂ film and the Pt film.

[3] The ferroelectric ceramics according to [1] or [2], wherein:

said ZrO₂ film is formed on a Si substrate; and

said Si substrate is oriented in (100).

[4] Ferroelectric ceramics including:

a Pt film formed on a CeO₂ film; and

a piezoelectric film formed on the Pt film.

[5] The ferroelectric ceramics according to [4], wherein:

a Ce₇O₁₂ film is formed under said CeO₂ film; and

a PtO₂ film is formed between said CeO₂ film and said Pt film.

[6] The ferroelectric ceramics according to [4] or [5], wherein:

said CeO₂ film is formed on a Si substrate;

said Si substrate is oriented in (100);

said CeO₂ film is oriented in (200); and

said Pt film is oriented in (200).

[7] The ferroelectric ceramics according to [5], wherein:

said Ce₇O₁₂ film is formed on a Si substrate;

said Si substrate is oriented in (100);

said Ce₇O₁₂ film is oriented in (300);

said CeO₂ film is oriented in (200);

said PtO₂ film is oriented in (200); and

said Pt film is oriented in (200).

[8] The ferroelectric ceramics according to [4], wherein a HfO₂ film isformed under said CeO₂ film or between said CeO₂ film and said Pt film.

[9] The ferroelectric ceramics according to [5], wherein a HfO₂ film isformed between said CeO₂ film and said PtO₂ film.

[10] The ferroelectric ceramics according to [8] wherein:

said CeO₂ film is formed on a Si substrate;

said Si substrate is oriented in (100);

said CeO₂ film is oriented in (200);

said HfO₂ film is oriented in (200); and

said Pt film is oriented in (200)

[11] The ferroelectric ceramics according to [9], wherein:

said Ce₇O₁₂ film is formed on a Si substrate;

said Si substrate is oriented in (100);

said Ce₇O₁₂ film is oriented in (300);

said CeO₂ film is oriented in (200);

said HfO₂ film is oriented in (200);

said PtO₂ film is oriented in (200); and

said Pt film is oriented in (200)

[12] Ferroelectric ceramics including:

a Pt film formed on a HfO₂ film; and

a piezoelectric film formed on the Pt film.

[13] The ferroelectric ceramics according to [12], wherein a PtO₂ filmis formed between said HfO₂ film and said Pt film.

[14] The ferroelectric ceramics according to [12] or [13], wherein:

said HfO₂ film is formed on a Si substrate;

said Si substrate is oriented in (100);

said HfO₂ film is oriented in (200); and

said Pt film is oriented in (200).

[15] The ferroelectric ceramics according to [13], wherein:

said HfO₂ film is formed on a Si substrate;

said Si substrate is oriented in (100);

said HfO₂ film is oriented in (200);

said PtO₂ film is oriented in (200); and

said Pt film is oriented in (200).

[16] A manufacturing method of ferroelectric ceramics, including thesteps of:

forming a ZrO₂ film on a Si substrate at a temperature of 550° C. orless, by an evaporation method;

forming a Pt film on the ZrO₂ film at a temperature of 550° C. or less,by sputtering; and

forming a piezoelectric film on the Pt film, wherein:

the ZrO₂ film is oriented in (200); and

the Pt film is oriented in (200).

[17] The manufacturing method of ferroelectric ceramics according to[16], wherein a PtO₂ film oriented in (200) is formed between the ZrO₂film and the Pt film.

Note that, in the above-described various aspects of the presentinvention, the phrase of forming a specified B (hereinafter, referred toas “B”) on (or under) a specified A (hereinafter, referred to as “A”)(or “B” is formed on (or under) “A”) is not limited to the case offorming “B” (the case where “B” is formed) directly on (or under) “A”,”but the phrase also includes the case of forming “B” (the case where “B”is formed) on (or under) “A” via another substance within the scope nothindering the working effect of the present invention.”

A piezoelectric film having excellent piezoelectric properties can beobtained by the application of one aspect of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-sectional view explaining a manufacturingmethod of ferroelectric ceramics according to one aspect of the presentinvention.

FIG. 2 is a schematic cross-sectional view explaining a manufacturingmethod of ferroelectric ceramics according to one aspect of the presentinvention.

FIG. 3 is an XRD (X-Ray Diffraction) chart of a sample in Example 1being an example of a first embodiment.

FIG. 4 is a schematic cross-sectional view explaining a manufacturingmethod of ferroelectric ceramics according to one aspect of the presentinvention.

FIG. 5 is a schematic cross-sectional view explaining a manufacturingmethod of ferroelectric ceramics according to one aspect of the presentinvention.

FIG. 6 is an XRD chart of a sample in Example 2 being an example of asecond embodiment.

FIG. 7 is a schematic cross-sectional view explaining a manufacturingmethod of ferroelectric ceramics according to one aspect of the presentinvention.

FIG. 8 is an XRD chart of a sample in Example 3.

FIG. 9 is a schematic cross-sectional view explaining a manufacturingmethod of ferroelectric ceramics according to one aspect of the presentinvention.

FIG. 10 is a schematic cross-sectional view explaining a manufacturingmethod of ferroelectric ceramics according to one aspect of the presentinvention.

FIG. 11 is an XRD chart of a sample in Example 4 being an example of afourth embodiment.

FIG. 12 is a schematic cross-sectional view explaining a manufacturingmethod of ferroelectric ceramics according to one aspect of the presentinvention.

FIG. 13 is a schematic cross-sectional view explaining a manufacturingmethod of ferroelectric ceramics according to one aspect of the presentinvention.

FIG. 14 is an XRD chart of a sample in Example 5 being an example of afifth embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, embodiments and Examples of the present invention will beexplained in detail using the drawings. However, a person skilled in theart would be able to easily understand that the present invention is notlimited to the following explanations but forms and details thereof maybe variously modified without deviating from the purport and the scopeof the present invention. Accordingly, the present invention is not tobe construed as being limited to the description of the embodiments andExamples, shown below.

(First Embodiment)

In Patent Literature 2 (Japanese Patent Laid-Open No. 11-312801),paragraph 0004, there is such description as below. When forming a Ptthin film directly on a ZrO₂ (001) thin film, the Pt becomes (111)-oriented or polycrystal and a Pt (100) single oriented film cannot beformed. This is because, since lattice mismatch between a ZrO₂ (001)plane and a Pt (100) plane is large, the Pt grows with a (111) planemore stable energetically as a growth plane, rather than the fact thatthe Pt epitaxially grows, that is, the Pt grows with (100) plane as agrowth plane.

The present inventors repeated hard developments, and succeeded inorienting the Pt film in (100) even when forming a Pt film directly on aZrO₂ film not having mixed with Y₂O₃. The Young's modulus of a ZrO₂ filmis 210 GPa but, in contrast, the Young's modulus of a YSZ film obtainedby mixing Y₂O₃ in ZrO₂ is from 400 to 440 GPa. Therefore, when a YSZfilm is formed on a substrate at a temperature of from 700° C. to 1000°C. (in Example 1 of Patent Literature 2, described as a temperature of900° C.) by an evaporation method and a piezoelectric film is formed onthe YSZ film, the resultant product becomes too hard as a substrate,whereas, when a ZrO₂ film is formed on a substrate at a temperature of500° C. and a piezoelectric film is formed on the ZrO₂ film, theresultant product is not too hard as a substrate and is easily used. TheYSZ film means a film that includes a mixture of Y₂O₃ and ZrO₂ obtainedby oxidation of Y and Zr with oxygen and that is in a stable state.

Note that, in the specification, being oriented in (100) and beingoriented in (200) are substantially equal to each other.

FIG. 1 is a schematic cross-sectional view explaining a manufacturingmethod of ferroelectric ceramics according to one aspect of the presentinvention.

A substrate 101 is prepared. Various kinds of substrates can be used asthe substrate, and there can be used, for example, substrates of asingle crystal such as a Si single crystal or a sapphire single crystal,substrates of a single crystal with a metal oxide film formed on thesurface thereof, substrates with a polysilicon film or a silicide filmformed on the surface thereof, and the like. Note that, in the presentembodiment, a Si substrate oriented in (100) is used.

Next, a ZrO₂ film (not shown) is formed on the Si substrate 101 at atemperature of 550° C. or less (preferably at 500° C.) by an evaporationmethod. The ZrO₂ film 102 is oriented in (200). Note that, when a ZrO₂film is formed at a temperature of 750° C. or more by an evaporationmethod, the ZrO₂ film is not oriented in (200).

After that, a Pt film 103 by epitaxial growth is formed on the ZrO₂ film102 at a temperature of 550° C. or less (preferably at 400° C.), bysputtering. The Pt film 103 is oriented in (200) (refer to FIG. 1). Atthis time, as shown in FIG. 2, a PtO₂ film 104 oriented in (200) may beformed between the ZrO₂ film 102 and the Pt film 103. Note that the Ptfilm 103 can be functioned as an electrode film.

By setting the substrate temperature to be 550° C. or less when formingthe ZrO₂ film 102 and the Pt film 103 and controlling the growth rateand thermal stress of the film to be low, as described above, it ispossible to orient the Pt film in (200) even when forming the Pt film103 directly on a ZrO₂ film 102 without the mixing of Y₂O₃.

Next, a PZT film (not shown) being an example of a piezoelectric film isformed on the Pt film 103. Note that, in the present specification, a“PZT film” also includes a film of a pure composition containing animpurity therein, and it is assumed that various impurities can beincorporated as long as the function of the piezoelectric body of a PZTfilm is not extinguished even when the impurity is incorporated.

Hereinafter, an example of a formation method of a PZT film will bespecifically explained.

As a sol-gel solution for forming the PZT film, there was used an E1solution having a concentration of 10% by weight, which contains butanolas a solvent and which is obtained by adding lead in an insufficientamount by 70% to 90%.

An alkaline alcohol having an amino group, referred to as dimethylaminoethanol, was added to the sol-gel solution at a ratio of E1 sol-gelsolution: dimethylamino ethanol=7:3 in a volume ratio, which exhibitedstrong alkalinity of pH=12.

A PZT amorphous film was formed using the above-described solution byspin coating. MS-A200 manufactured by MIKASA CO., LTD. was used as aspin coater. First, the coater was rotated at 800 rpm for 5 seconds andat 1500 rpm for 10 seconds, then the rotational speed was raisedgradually to 3000 rpm in 10 seconds, which was left on a hot plate(AHS-300, a ceramic hot plate manufactured by AS ONE Corporation) at150° C. for 5 minutes in the air, after that, was left on a hot plate(AHS-300) at 300° C. for 10 minutes also in the air, and subsequently,was cooled to room temperature. The process was repeated five times tothereby form a PZT amorphous film having an intended thickness of 200 nmon the Pt film 103. The product was formed in plural number.

Next, a heat treatment was performed on the above-described PZTamorphous film in a pressurized oxygen atmosphere to thereby form a PZTfilm obtained by crystallizing the PZT amorphous film, on the Pt film103. Note that an example of the lattice constant of PZT is 0.401 nm.

After forming a PZT film as described above, the PZT film may besubjected to a polling processing.

According to the present embodiment, since the Pt film 103 is orientedin (100) or (200), a piezoelectric film having excellent piezoelectricproperties can be obtained by forming a PZT film as a piezoelectric filmon the Pt film 103.

Furthermore, the use of the ZrO₂ film 102 having a low Young's modulusas low as a half of that of Y₂O₃ is advantageous in that the movement ofthe piezoelectric film is not prevented. Moreover, no mixing of anotherelement such as Y other than Zr is also advantageous in thatcontamination is suppressed. In addition, very low unit price by gram ofZr is also advantageous in that the cost is suppressed.

EXAMPLE 1

FIG. 3 is an XRD (X-Ray Diffraction) chart of a sample in Example 1 ofthe present embodiment. In FIG. 3, the vertical axis shows intensity andthe horizontal axis shows 2θ. The sample was produced as follows.

A ZrO₂ film was formed on a Si wafer having a (100) crystal plane by areactive evaporation method. Evaporation conditions at this time are asshown in Table 1. The ZrO₂ film was oriented in (200).

Subsequently, a Pt film was formed on the ZrO₂ film, by sputtering.Conditions of film formation at this time are as shown in Table 1. ThePt film was oriented in (200).

TABLE 1 EXAMPLE Process EVAPORATION DC-SPUTTERING Depo Vac 6.90E−033.20E−02 Depo Source Zr + O₂ Pt ACC/Emission 7.5 kV/1.50 mA DC/100 WTotal Thickness (nm) 13.4 150 Depo Time (sec) 930 720 SV deg (Tsub) 500°C. 400° C. MFC O₂ 5 sccm Ar: 16 sccm

The XRD chart shown in FIG. 3 shows a result of XRD of a sample obtainedby forming only the ZrO₂ film (only a buffer layer), and a result of XRDof a sample obtained by carried out the formation up to the Pt film(after the growth up to the Pt layer). From the XRD chart, it wasconfirmed that the Si wafer was oriented in (200), that the ZrO₂ filmwas oriented in (200), and that the Pt film was oriented in (200), andit was confirmed that a PtO₂ film oriented in (200) was formed.

According to the Example, it becomes possible to form, on the Pt film, aPZT film having very good crystallinity and excellent piezoelectricproperties by orienting the Pt film in (200).

(Second Embodiment)

FIG. 4 is a schematic cross-sectional view explaining a manufacturingmethod of ferroelectric ceramics according to one aspect of the presentinvention, in which the same sign is attached to the same portion asthat in FIG. 1 and the explanation thereof is omitted.

A CeO₂ film 105 is formed on the Si substrate 101 by an evaporationmethod. The CeO₂ film 105 is oriented in (200) (refer to FIG. 4). Atthis time, as shown in FIG. 5, a Ce₇O₁₂ film 106 oriented in (300) maybe formed between the Si substrate 101 and the CeO₂ film 105. Note that,in the present embodiment, the CeO₂ film 105 is formed on the Sisubstrate 101, but the embodiment is not limited to this, and a ZrO₂film may be formed between the Si substrate 101 and the CeO₂ film 105 byan evaporation method. Furthermore, in the present embodiment, the CeO₂film 105 is formed by an evaporation method, but the CeO₂ film 105 maybe formed by an ion beam sputtering or radio-frequency (RF) sputtering.

After that, the Pt film 103 by epitaxial growth is formed on the CeO₂film 105, by sputtering. The Pt film 103 is oriented in (200) (refer toFIG. 4). At this time, as shown in FIG. 5, the PtO₂ film 104 oriented in(200) maybe formed between the CeO₂ film 105 and the Pt film 103.

The Pt film 103 can be oriented in (200) by forming the Pt film 103 onthe CeO₂ film 105 as described above.

Next, a PZT film (not shown) being an example of a piezoelectric film isformed on the Pt film 103.

According to the present embodiment, since the Pt film 103 is orientedin (100) or (200), a piezoelectric film having excellent piezoelectricproperties can be obtained by forming a PZT film as a piezoelectric filmon the Pt film 103.

EXAMPLE 2

FIG. 6 is an XRD chart of a sample in Example 2 of the presentembodiment. In FIG. 6, the vertical axis shows intensity and thehorizontal axis shows 2θ. The sample was produced as follows.

A CeO₂ film was formed on a Si wafer having a (100) crystal plane by areactive evaporation method. Evaporation conditions at this time are asshown in Table 2. The CeO₂ film was oriented in (200).

Subsequently, a Pt film was formed on the CeO₂ film, by sputtering.Conditions of film formation at this time are as shown in Table 2. ThePt film was oriented in (200).

TABLE 2 EXAMPLE Process EVAPORATION DC-SPUTTERING Depo Vac 6.90E−033.20E−02 Depo Source Ce + O₂ Pt ACC/Emission 7.5 kV/1.50 mA DC/100 WTotal Thickness (nm) 13.4 150 Depo Time (sec) 930 720 SV deg (Tsub) 500°C. 400° C. MFC O₂ 5 sccm Ar: 16 sccm

The XRD chart shown in FIG. 6 shows a result of XRD of a sample obtainedby forming only the CeO₂ film, and a result of XRD of a sample obtainedby carried out the formation up to the Pt film. From the XRD chart, itwas confirmed that the CeO₂ film was oriented in (200), and that the Ptfilm was oriented in (200), and it was confirmed that a Ce₇O₁₂ filmoriented in (300) was formed and a PtO₂ film oriented in (200) wasformed.

According to the Example, it becomes possible to form, on the Pt film, aPZT film having excellent piezoelectric properties, by orienting the Ptfilm in (200).

(Third Embodiment)

FIG. 7 is a schematic cross-sectional view explaining a manufacturingmethod of ferroelectric ceramics according to one aspect of the presentinvention, in which the same sign is attached to the same portion asthat in each of FIGS. 1, 4 and 5 and the explanation thereof is omitted.

The ZrO₂ film 102 is formed on the Si substrate 101 by an evaporationmethod in the same way as that in the first embodiment. The ZrO₂ film102 is oriented in (200).

Next, the CeO₂ film 105 is formed on the ZrO₂ film 102 by an evaporationmethod in the same way as that in the second embodiment. The CeO₂ film105 is oriented in (200).

Subsequently, the Pt film 103 is formed on the CeO₂ film 105 in the sameway as that in the second embodiment. The Pt film 103 is oriented in(200). At this time, the PtO₂ film 104 oriented in (200) is formedbetween the CeO₂ film 105 and the Pt film 103.

Next, a Sr(Ti_(1-x)Ru_(x))O₃ film (STRO) is formed on the Pt film 103,by sputtering. Note that the x satisfies a formula 1 below. Furthermore,a sintered body of a Sr(Ti_(1-x)Ru_(x))O₃ is used as a sputtering targetat this time. However, the x satisfies the formula 1 below.0.01≦x≦0.4(preferably 0.05≦x≦0.2)  formula 1

Note that the reason why the x in the Sr(Ti_(1-x)Ru_(x))O₃ film 111 is0.4 or less is because, when the x is set to exceed 0.4, the firstSr(Ti_(1-x)Ru_(x))O₃ film becomes powdery and cannot sufficiently besolidified.

After that, the Sr(Ti_(1-x)Ru_(x))O₃ film 111 is crystallized by RTA(Rapid Thermal Anneal) in a pressurized oxygen atmosphere.

The Sr(Ti_(1-x)Ru_(x))O₃ film 111 is a film of a complex oxide ofstrontium, titanium and ruthenium, the complex oxide being a compoundhaving a perovskite structure.

Next, a PZT film (not shown) being an example of a piezoelectric film isformed on the Sr(Ti_(1-x)Ru_(x))O₃ film 111.

According to the present embodiment, since the Sr(Ti_(1-x)Ru_(x))O₃ film111 is oriented in (100) or (200), a piezoelectric film having excellentpiezoelectric properties can be obtained by forming a PZT film as apiezoelectric film on the Sr(Ti_(1-x)Ru_(x))O₃ film 111.

EXAMPLE 3

FIG. 8 is a chart showing a result of XRD (X-Ray Diffraction) of asample in Example 3. In FIG. 8, the vertical axis shows intensity andthe horizontal axis shows 2θ. The sample was produced as follows.

A ZrO₂ film was formed on a Si wafer having a (100) crystal plane by areactive evaporation method. Evaporation conditions at this time are asshown in Table 1. The ZrO₂ film was oriented in (200).

Then, a CeO₂ film was formed on the ZrO₂ film, by a reactive evaporationmethod. Evaporation conditions at this time are as shown in Table 2. TheCeO₂ film was oriented in (200).

Subsequently, a Pt film was formed on the CeO₂ film, by sputtering.Conditions of film formation at this time are as shown in Table 2. ThePt film was oriented in (200).

Next, a Sr(Ti_(0.8)Ru_(0.2))O₃ film was formed on the Pt film, bysputtering. Furthermore, a first Sr(Ti_(0.95)Ru_(0.05))O₃ film wasformed on the Pt film of a sample 2, by sputtering. Conditions ofsputtering at this time are as follows.

[STRO Sputtering Conditions]

Process: RF sputtering

Target: Sr(Ti_(0.8)Ru_(0.2))O₃

RF power: 400 W/13.56 MHz

Process pressure: 4 Pa

Gas flow rate Ar/O₂ (sccm): 30/10

Substrate temperature: 600° C.

Process time: 20 sec

Film thickness: 50 nm

After that, the Sr(Ti_(0.8)Ru_(0.2))O₃ film was crystallized by RTA in apressurized oxygen atmosphere. Conditions of the RTA at this time are asfollows.

[RTA Conditions]

Annealing temperature: 600° C.

Introduced gas: oxygen gas

Pressure: 9 kg/cm²

Temperature rising rate: 100 ° C/sec

Annealing time: 5 minutes

From the XRD chart shown in FIG. 8, it was confirmed that theSr(Ti_(0.8)Ru_(0.2))O₃ film was oriented in (100), that the CeO₂ filmwas oriented in (200), that the ZrO₂ film was oriented in (200) and thePt film is oriented in (200), and, furthermore, it was confirmed that aPtO₂ film oriented in (200) was formed.

According to the Example, it becomes possible to form a PZT film havingexcellent piezoelectric properties on the Sr(Ti_(0.8)Ru_(0.2))O₃ film,by orienting a Sr(Ti_(0.8)Ru_(0.2))O₃ film in (100).

(Fourth Embodiment)

FIG. 9 is a schematic cross-sectional view explaining a manufacturingmethod of ferroelectric ceramics according to one aspect of the presentinvention, in which the same sign is attached to the same portion asthat in FIG. 1, and the explanation thereof is omitted.

A HfO₂ film 107 is formed on the Si substrate 101, by an evaporationmethod. The HfO₂ film 107 is oriented in (200) Note that, in the presentembodiment, the HfO₂ film 107 is formed on the Si substrate 101, but theembodiment is not limited to this, and a ZrO₂ film may be formed betweenthe Si substrate 101 and the HfO₂ film 107, by an evaporation method.Furthermore, in the present embodiment, the HfO₂ film 107 is formed byan evaporation method, but the HfO₂ film 107 maybe formed by an ion beamsputtering or radio-frequency (RF) sputtering.

After that, the Pt film 103 by epitaxial growth is formed on the HfO₂film 107, by sputtering. The Pt film 103 is oriented in (200) (refer toFIG. 9). At this time, as shown in FIG. 10, the PtO₂ film 104 orientedin (200) maybe formed between the HfO₂ film 107 and the Pt film 103.

The Pt film 103 can be oriented in (200) by forming the Pt film 103 onthe HfO₂ film 107 as described above.

Next, a PZT film (not shown) being an example of a piezoelectric film isformed on the Pt film 103.

According to the present embodiment, since the Pt film 103 is orientedin (100) or (200), a piezoelectric film having excellent piezoelectricproperties can be obtained by forming a PZT film as a piezoelectric filmon the Pt film 103.

EXAMPLE 4

FIG. 11 is an XRD chart of a sample in Example 4 of the presentembodiment. In FIG. 11, the vertical axis shows intensity and thehorizontal axis shows 20. The sample was produced as follows.

A HfO₂ film was formed on a Si wafer having a (100) crystal plane by areactive evaporation method. Evaporation conditions at this time are asshown in Table 3. The HfO₂ film was oriented in (200).

Subsequently, a Pt film was formed on the HfO₂ film, by sputtering.Conditions of film formation at this time are as shown in Table 3. ThePt film was oriented in (200)

TABLE 3 EXAMPLE Process EVAPORATION DC-SPUTTERING Depo Vac 6.90E−033.20E−02 Depo Source Hf + O₂ Pt ACC/Emission 7.5 kV/1.50 mA DC/100 WTotal Thickness (nm) 13.4 150 Depo Time (sec) 930 720 SV deg (Tsub) 500°C. 400° C. MFC O₂ 5 sccm Ar: 16 sccm

The XRD chart shown in FIG. 11 shows a result of XRD of a sampleobtained by forming only a HfO₂film, and a result of XRD of a sampleobtained by carried out the formation up to the Pt film. From the XRDchart, it was confirmed that the Si wafer was oriented in (200), thatthe HfO₂ film was oriented in (200), and that the Pt film was orientedin (200), and it was confirmed that a PtO₂ film oriented in (200) wasformed.

According to the Example, it becomes possible to form, on the Pt film, aPZT film having excellent piezoelectric properties, by orienting the Ptfilm in (200).

(Fifth Embodiment)

FIG. 12 is a schematic cross-sectional view explaining a manufacturingmethod of ferroelectric ceramics according to one aspect of the presentinvention, in which the same sign is attached to the same portion asthat in FIG. 1 and the explanation thereof is omitted.

A CeO₂ film 105 is formed on the Si substrate 101, by an evaporationmethod. The CeO₂ film 105 is oriented in (200) (refer to FIG. 12). Atthis time, as shown in FIG. 13, a Ce₇O₁₂ film 106 oriented in (300) maybe formed between the Si substrate 101 and the CeO₂ film 105. Note that,in the present embodiment, the CeO₂ film 105 is formed on the Sisubstrate 101, but the embodiment is not limited to this, and a ZrO₂film may be formed between the Si substrate 101 and the CeO₂ film 105,by an evaporation method.

Next, a HfO₂ film 107 is formed on the CeO₂ film 105, by an evaporationmethod. The HfO₂ film 107 is oriented in (200). Note that, in thepresent embodiment, the CeO₂ film 105 and the HfO₂ film 107 are formedby an evaporation method, but the CeO₂ film 105 and the HfO₂ film 107may be formed by an ion beam sputtering or radio-frequency (RF)sputtering.

After that, the Pt film 103 by epitaxial growth is formed on the HfO₂film 107, by sputtering. The Pt film 103 is oriented in (200) (refer toFIG. 12). At this time, as shown in FIG. 13, the PtO₂ film 104 orientedin (200) may be formed between the HfO₂ film 107 and the Pt film 103.

The Pt film 103 can be oriented in (200) by forming the Pt film 103 onthe HfO₂ film 107 as described above.

Next, a PZT film (not shown) being an example of a piezoelectric film isformed on the Pt film 103.

According to the present embodiment, since the Pt film 103 is orientedin (100) or (200), a piezoelectric film having excellent piezoelectricproperties can be obtained by forming a PZT film as a piezoelectric filmon the Pt film 103.

Note that, in the present embodiment, the CeO₂ film 105, the HfO₂ film107 and the Pt film 103 are formed on the Si substrate 101, in thisorder, but the embodiment is not limited to this, and the HfO₂ film 107,the CeO₂ film 105 and the Pt film 103 may be formed on the Si substrate101, in this order.

EXAMPLE 5

FIG. 14 is an XRD chart of a sample in Example 5 of the presentembodiment. In FIG. 14, the vertical axis shows intensity and thehorizontal axis shows 2θ. The sample was produced as follows.

A CeO₂ film was formed on a Si wafer having a (100) crystal plane, by areactive evaporation method. Evaporation conditions at this time are thesame as those in Example 2. The CeO₂ film was oriented in (200).

Subsequently, a HfO₂ film was formed on the CeO₂ film, by a reactiveevaporation method. Evaporation conditions at this time are the same asthose in Example 4. The HfO₂ film was oriented in (200).

Then, a Pt film was formed on the HfO₂ film, by sputtering. Conditionsof film formation at this time are the same as those in Example 4. ThePt film was oriented in (200).

The XRD chart shown in FIG. 14 shows a result of XRD f a sample obtainedby carried out the formation up to the HfO₂ film, and a result of XRD ofa sample obtained by carried out the formation up to the Pt film. Fromthe XRD chart, it was confirmed that the CeO₂ film was oriented in(200), that the HfO₂ film was oriented in (200), and that the Pt filmwas oriented in (200), and it was confirmed that a Ce₇O₁₂ film orientedin (300) was formed and a PtO₂ film oriented in (200) was formed.

According to the Example, it becomes possible to form a PZT film havingexcellent piezoelectric properties on a Pt film by orienting the Pt filmin (200).

Note that above-described first to fifth embodiments may appropriatelybe combined and carried out.

DESCRIPTION OF REFERENCE SYMBOLS

-   101 Si substrate-   102 ZrO₂ film-   103 Pt film-   104 PtO₂ film-   105 CeO₂ film-   106 Ce₇O₁₂ film-   107 HfO₂ film-   111 Sr(Ti_(1-x)Ru_(x))O₃ film (STRO)

The invention claimed is:
 1. Ferroelectric ceramics comprising: a ZrO₂film oriented in (200); a PtO₂ film that is formed directly on said ZrO₂film and is oriented in (200); a Pt film that is formed on said PtO₂film and is oriented in (200); and a piezoelectric film formed on saidPt film.
 2. The ferroelectric ceramics according to claim 1, wherein aSr(Ti_(1-x)Ru_(x))O₃ film oriented in (200) is formed between said Ptfilm and said piezoelectric film, and x satisfies formula 1:0.01≦x≦0.4  formula 1.